HEATING THE RANGE 115 



88. High pressure steam at boilers with reduced pres- 

 sure in greenhouses, and pumped returns. " High pres- 

 sure steam is not adaptable for use in radiation in green- 

 houses, for the heat is far too intense. However, high 

 pressure steam is often used with a reducing-valve, so the 

 average temperature inside the greenhouses is considerably 

 less than that in the mains or at the boiler. It is then 

 found necessary to use a pump to return the water of 

 condensation, and this pump may be operated by the 

 high pressure steam. The pipe coils are distributed 

 through the greenhouse in the same manner with this 

 svstem as with other steam systems." 



